Thank you for the link. I did find that following code on that site that might do the trick.
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The issue with CSS Styling is that it's not changing the data, and if you don't want to have a JS function then try...

<input onkeyup="this.value = this.value.toUpperCase()" />

on it's own you'll see the field capitalise on keyup, so it might be desirable to combine this with the style='text-transform:uppercase' others have suggested.
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